Packetized content delivery apparatus and methods

ABSTRACT

Apparatus and methods for delivery of content in a packetized network. In one embodiment, content and/or services can be associated with an IP address. The IP address may be assigned to multiple server devices disposed at geographically diverse locations. Delivery caches may advertise, via a routing protocol, one or more addresses to clients of the network. Route selection may be configured based on one or more rules such as geographical proximity, available bandwidth, server availability, server load, delivery cost, client subscription level, licensing rules, and/or other metric. Delivery caches may be configured to control their availability and/or load through IP address withdrawals and announcements. When the “closest” delivery cache may become unavailable (e.g., it is not announcing the IP address for the content the client is trying to obtain, a route to the next “closest” available delivery cache may be utilized.

PRIORITY

This application is a continuation of and claims priority to co-ownedand co-pending U.S. patent application Ser. No. 13/958,467 filed on Aug.2, 2013 of the same title, issuing as U.S. Pat. No. 9,467,369 on Oct.11, 2016, which is incorporated herein by reference in its entirety.

COPYRIGHT

A portion of the disclosure of this patent document contains materialthat is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent files or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND

1. Technological Field

The present disclosure relates generally to the field of content and/ordata delivery over a network. More particularly, the present disclosureis related, in one exemplary aspect, to apparatus and methods forpacketized content delivery via a network.

2. Description of Related Technology

The provision of content to a plurality of subscribers in a contentdistribution network is well known in the prior art. In a typicalconfiguration, the content is distributed to the subscribers devicesover any number of different topologies including for example: (i)Hybrid Fiber Coaxial (HFC) network, which may include e.g., dense wavedivision multiplexed (DWDM) optical portions, coaxial cable portions,and other types of bearer media; (ii) satellite network (e.g., from anorbital entity to a user's STB via a satellite dish); (iii) opticalfiber distribution networks such as e.g., “Fiber to the X” or FTTx(which may include for example FTTH, FTTC, FTTN, and FTTB variantsthereof); (iv) Hybrid Fiber/copper or “HFCu” networks (e.g., afiber-optic distribution network, with node or last-mile delivery beingover installed POTS/PSTN phone wiring or CAT-5 cabling); (v)microwave/millimeter wave systems; etc.

Various types of content delivery services are utilized in providingcontent to subscribers. For example, certain content may be providedaccording to a broadcast schedule (aka “linear” content). Content mayalso be provided on-demand (such as via video on-demand or VOD, freevideo on-demand, near video on-demand, etc.). Content may also beprovided to users from a recording device located at a user premises(such as via a DVR) or elsewhere (such as via a personal video recorderor network personal video recorder disposed at a network location) orvia a “startover” paradigm, which also affords the user increasedcontrol over the playback of the content (“non-linear”).

Various systems and methods may be utilized for delivering media contentto subscribers. For example, so-called “Internet Protocol Television” or“IPTV” is a system through which services are delivered to subscribersusing the architecture and networking methods of an Internet ProtocolSuite over a packet-switched network infrastructure (such as e.g., theInternet and broadband Internet access networks), instead of beingdelivered through traditional radio frequency broadcast, satellitesignal, or cable television (CATV) formats. These services may include,for example, Live TV, Video On-Demand (VOD), and Interactive TV (iTV).IPTV delivers services (including video, audio, text, graphics, data,and control signals) across an access agnostic, packet switched networkthat employs the IP protocol.

Some existing content delivery network (CDN) solutions (e.g., Velocix)utilize proprietary software and/or hardware. Furthermore, in order tosupport advanced functionality (e.g., multi-tenancy, and/or other), someexisting CDN may employ a centralized control system. Use of centralizedcontrol may increase deployment costs, system complexity, and/or reduceresponse time when adding features, responding to failures, and/orperforming maintenance.

Accordingly, less costly, more flexible and scalable content deliveryimplementation that may be deployed utilizing commercial off the shelfhardware and without relying proprietary software and/or hardwareimplementations would be of benefit.

SUMMARY

The present disclosure addresses the foregoing needs by disclosing,inter alia, anycast apparatus and methods for packetized contentdelivery.

In one aspect of the disclosure, a method of providing content in apacket-enabled network is disclosed. In one embodiment, the methodincludes: associating the content with an address within the network;assigning the address to two or more nodes of the network, individualones of the two or more nodes configured to deliver the content to aclient of the network; advertising two or more routes associated withtwo or more nodes, individual ones of the two or more routes beingcharacterized by the address; and based on a selection of a given routeof the two or more routes, causing delivery of the content to the clientby a node of the two or more nodes, the node corresponding to the givenroute.

In another aspect of the disclosure, a content delivery network isdisclosed. In one embodiment, the network includes: at least onedelivery cache in operable communication with a client device, thedelivery cache configured to effectuate provision of content to theclient device; and at least one first tier cache in operablecommunication with the delivery cache, the first tier cache configuredto effectuate provision of the content to the delivery cache. In onevariant, the at least one delivery cache is accessible by the clientusing an Internet Protocol (IP) address; and the at least one first tiercache is accessible by the delivery cache.

In a further aspect, a non-transitory computer-readable apparatusconfigured to store one or more computer programs thereon is disclosed.In one embodiment, the one or more computer programs include a pluralityof instructions configured to, when executed: based on a request towithdraw an active route from a pool of active routes of a network,determine a network address associated with the route; determineexistence of another active route of the pool of active routes; andeffectuate withdrawal of the active route from the pool of active routesbased at least on the determination of the existence of the anotheractive route. In one variant, the active route and another active routeare configured to provide content associated with the network address toa client of the network; and the determination of existence of theanother active route is based at least on the existence of the route asadvertised from a different delivery cache.

In yet another aspect, an “anycast” network architecture is disclosed.In one variant, the network comprises a content delivery network, andincludes a multi-tiered configuration with the capability ofdistributing content to network clients via a plurality of routes.

In a further aspect, a method of operating a network is disclosed. Inone embodiment, the network includes delivery caches that are configuredto control their availability and/or load through IP address withdrawalsand announcements. When the “closest” delivery cache becomes unavailable(e.g., it is not announcing the IP address for the content the client istrying to obtain), a route to the next “closest” available deliverycache may be utilized.

In another aspect, a method of mitigating IP address “stranding” in acontent distribution network is disclosed.

These and other aspects become apparent when considered in light of thedisclosure provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram illustrating an exemplary hybridfiber network configuration useful with various aspects of the presentdisclosure.

FIG. 1a is a functional block diagram illustrating one exemplary networkheadend configuration.

FIG. 1b is a functional block diagram illustrating one exemplary localservice node configuration useful with various aspects of the presentdisclosure.

FIG. 1c is a functional block diagram illustrating one exemplarybroadcast switched architecture (BSA) network.

FIG. 1d is a functional block diagram illustrating one exemplarypacketized content delivery network architecture useful with variousaspects of the present disclosure.

FIG. 1e is a functional block diagram illustrating a second exemplarypacketized content delivery network architecture useful with variousaspects of the present disclosure.

FIG. 2 is a functional block diagram depicting an exemplary “anycast”network architecture for delivery of packetized content in accordancewith one or more implementations.

FIG. 3 is a functional block diagram illustrating an exemplary routeadvertisement and client flow in a content delivery network inaccordance with one or more implementations

FIG. 4 is a functional block diagram depicting an exemplary hierarchicalcaching process in a content delivery network in accordance with one ormore implementations.

FIG. 5 is a functional block diagram depicting an exemplary VODpre-seeding process in an anycast CDN in accordance with one or moreimplementations.

FIG. 6 is a logical flow diagram illustrating an exemplary method forcontent retrieval by a client of anycast CDN in accordance with one ormore implementations.

FIG. 7 is a logical flow diagram illustrating an exemplary method fornode maintenance in anycast CDN in accordance with one or moreimplementations.

FIG. 8 is a logical flow diagram illustrating an exemplary method forcontent provision in anycast CDN comprising hierarchical cache inaccordance with one or more implementations.

FIG. 9 is a functional block diagram depicting an exemplary nodeapparatus of packetized network useful for providing content usinganycast methodology in accordance with one or more implementations.

All Figures © Copyright 2013 Time Warner Cable, Inc. All rightsreserved.

DETAILED DESCRIPTION

Reference is now made to the drawings wherein like numerals refer tolike parts throughout.

As used herein, the term “application” refers generally and withoutlimitation to a unit of executable software that implements a certainfunctionality or theme. The themes of applications vary broadly acrossany number of disciplines and functions (such as on-demand contentmanagement, e-commerce transactions, brokerage transactions, homeentertainment, calculator etc.), and one application may have more thanone theme. The unit of executable software generally runs in apredetermined environment; for example, the unit could comprise adownloadable Java Xlet™ that runs within the JavaTV™ environment.

As used herein, the terms “client device” and “end user device” include,but are not limited to, set top boxes (e.g., DSTBs), personal computers(PCs), and minicomputers, whether desktop, laptop, or otherwise, andmobile devices such as handheld computers, tablets, “phablets”, PDAs,personal media devices (PMDs), and smartphones.

As used herein, the term “computer program” or “software” is meant toinclude any sequence or human or machine cognizable steps which performa function. Such program may be rendered in virtually any programminglanguage or environment including, for example, C/C++, Fortran, COBOL,PASCAL, assembly language, markup languages (e.g., HTML, SGML, XML,VoXML), and the like, as well as object-oriented environments such asthe Common Object Request Broker Architecture (CORBA), Java™ (includingJ2ME, Java Beans, etc.), Binary Runtime Environment (e.g., BREW), andthe like.

The term “Customer Premises Equipment (CPE)” refers to any type ofelectronic equipment located within a customer's or user's premises andconnected to a network, such as set-top boxes (e.g., DSTBs or IPTVdevices), televisions, cable modems (CMs), embedded multimedia terminaladapters (eMTAs), whether stand-alone or integrated with other devices,Digital Video Recorders (DVR), gateway storage devices (Furnace), andITV Personal Computers.

As used herein, the term “display” means any type of device adapted todisplay information, including without limitation CRTs, LCDs, TFTs,plasma displays, LEDs, OLEDs, incandescent and fluorescent devices.Display devices may also include less dynamic devices such as, forexample, printers, e-ink devices, and the like.

As used herein, the terms “Internet” and “internet” are usedinterchangeably to refer to inter-networks including, withoutlimitation, the Internet.

As used herein, the term “memory” or “storage” includes any type ofintegrated circuit or other storage device adapted for storing digitaldata including, without limitation, ROM. PROM, EEPROM, DRAM, SDRAM,DDR/2 SDRAM, EDO/FPMS, RLDRAM, SRAM, “flash” memory (e.g., NAND/NOR),and PSRAM.

As used herein, the terms “microprocessor” and “digital processor” aremeant generally to include all types of digital processing devicesincluding, without limitation, digital signal processors (DSPs), reducedinstruction set computers (RISC), general-purpose (CISC) processors,microprocessors, gate arrays (e.g., FPGAs), PLDs, reconfigurable computefabrics (RCFs), array processors, and application-specific integratedcircuits (ASICs). Such digital processors may be contained on a singleunitary IC die, or distributed across multiple components.

As used herein, the terms “MSO” or “multiple systems operator” referwithout limitation to a cable, satellite, or terrestrial networkprovider having infrastructure required to deliver services includingprogramming and data over those mediums.

As used herein, the terms “network” and “bearer network” refer generallyto any type of telecommunications or data network including, withoutlimitation, hybrid fiber coax (HFC) networks, satellite networks, telconetworks, and data networks (including MANs, WANs, LANs, WLANs,internets, and intranets). Such networks or portions thereof may utilizeany one or more different topologies (e.g., ring, bus, star, loop,etc.), transmission media (e.g., wired/RF cable, RF wireless, millimeterwave, optical, etc.) and/or communications or networking protocols(e.g., SONET, DOCSIS, IEEE Std. 802.3, ATM, X.25, Frame Relay, 3GPP,3GPP2, LTE/LTE-A, WAP, SIP, UDP, FTP, RTP/RTCP, H.323, etc.).

As used herein, the term “network interface” refers to any signal ordata interface with a component or network including, withoutlimitation, those of the Firewire (e.g., FW400, FW800, etc.), USB (e.g.,USB2), Ethernet (e.g., 10/100, 10/100/1000 (Gigabit Ethernet), 10-Gig-E,etc.), MoCA, Serial ATA (e.g., SATA, e-SATA, SATAII), Ultra-ATA/DMA,Coaxsys (e.g., TVnet™), radio frequency tuner (e.g., in-band or OOB,cable modem, etc.), Wi-Fi (802.11a,b,g,n), Wi-MAX (802.16), PAN(802.15), cellular (e.g., LTE/LTE-A, 3GPP, 3GPP2, UMTS), or IrDAfamilies.

As used herein, the term “server” refers to any computerized component,system or entity regardless of form which is adapted to provide data,files, applications, content, or other services to one or more otherdevices or entities on a computer network.

As used herein, the term “user interface” refers to, without limitation,any visual, graphical, tactile, audible, sensory, or other means ofproviding information to and/or receiving information from a user orother entity.

As used herein, the term “Wi-Fi” refers to, without limitation, any ofthe variants of IEEE-Std. 802.11 or related standards including 802.11a/b/g/n/v.

As used herein, the term “wireless” means any wireless signal, data,communication, or other interface including without limitation Wi-Fi,Bluetooth, 3G (3GPP/3GPP2), HSDPA/HSUPA, TDMA, CDMA (e.g., IS-95A,WCDMA, etc.), FHSS, DSSS, GSM, PAN/802.15, WiMAX (802.16), 802.20, NFC(e.g., ISO 14443A/B), narrowband/FDMA, OFDM, PCS/DCS, LTE/LTE-A/TD-LTE,analog cellular, Zigbee, CDPD, satellite systems, millimeter wave ormicrowave systems, acoustic, and infrared (i.e., IrDA).

OVERVIEW

In one salient aspect, the present disclosure provides apparatus andmethods for content delivery in a packetized network. In one exemplaryincarnation, a content and/or a service is associated with an IPaddress. The IP address may be assigned to multiple server devices thatmay be disposed at geographically diverse locations. Delivery caches mayadvertise, via e.g., a routing protocol, one or more addresses toclients of the network and/or other network entities. Route selectioncan be configured based on one or more rules, such as for example thoserelating to geographical proximity, available bandwidth, serveravailability, server load, delivery cost, client subscription level,content encoding rate (e.g., MPEG2, MPEG4, and/or other), client devicetype (e.g., a smartphone, a television), client connection bandwidth(e.g., LTE, Wi-Fi), client subscription level, and/or other ruleslicensing rules, and/or other metric.

Delivery caches are in an exemplary embodiment configured to controltheir availability and/or load through IP address withdrawals andannouncements. When the “closest” delivery cache becomes unavailable(e.g., it is not announcing the IP address for the content the client istrying to obtain), a route to the next “closest” available deliverycache may be utilized. In some implementations, a combination ofroute-monitoring and a fallback delivery cache is employed to reduceand/or prevent IP address “stranding”.

Delivery nodes may provide multiple service functions by advertisingroutes out of an assigned address pool assigned to individual servicefunctions. By statically setting two or more advertised addresses for anindividual delivery cache, delivery address availability address may beensured when a given cache may fail, and/or withdraw its addresses fromthe advertised pool. However, this may be depreciated given theroute-monitoring method discussed above.

In some implementations, hierarchical caching is supported. Contentavailability may be advertised via a mechanism such as e.g., bordergateway protocol (BGP) announcements of pools of addresses. Access todifferent levels of cache hierarchy can be effectuated through the useof different pools of addresses. Proxy-enabled web servers enableselection of a backfill source based on the path being requested. In onevariant, a hierarchical cache is configured to serve as a client facingdelivery cache by advertising a route from an appropriate address pool.Hierarchical caches could also service client requests by advertisingsome subset of service function pool addresses.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the apparatus and methods of the presentdisclosure are now described in detail. While these exemplaryembodiments are described in the context of a managed hybrid fiber coax(HFC) cable system architecture having a multiple systems operator,digital networking capability, and plurality of client devices/CPE, thegeneral principles and advantages of the disclosure may be extended toother types of networks and architectures, whether broadband,narrowband, wired or wireless, terrestrial or satellite, managed orunmanaged (or combinations thereof), or otherwise, the followingtherefore being merely exemplary in nature.

It will also be appreciated that while described generally in thecontext of institutional service provision (e.g. academic, commercial,government, non-profit, etc.), the present disclosure may be readilyadapted to other types of environments (e.g., home networks, etc.) aswell. Myriad other applications are possible.

Further, although described in the context of service provision over anexternally managed network, the architectures and techniques describedherein may be readily applied to internal network management. Theexternal managed network embodiments presented are merely used todemonstrate the flexibility and general applicability of the principlesdescribed herein (e.g. may be implemented with or without fulladministrator control of a network), and should not be considered in anyway limiting.

In addition, while the disclosure refers at numerous points to one ormore internet protocol television (IPTV) embodiments, the principles ofthe disclosure are contemplated in other applications, such as videoservices (e.g., network DVR, second screen apps, cloud based digitalnavigators, OnDemand or over-the-top (OTT) content (e.g., Netflix®,Hulu®, virtual MSO services, and/or other)), visual communications(i.e., Skype®, Facetime®, and/or other), or cloudcomputing/storage/streaming services. All such embodiments areconsidered disclosed herein.

Also, while certain aspects are described primarily in the context ofthe well-known Internet Protocol (described in, inter alia, RFC 791 and2460), it will be appreciated that the present disclosure may utilizeother types of protocols (and in fact bearer networks to include otherinternets and intranets) to implement the described functionality.

Bearer Network—

FIG. 1 illustrates a typical content delivery network configuration. Thevarious components of the network 100 include (i) one or more data andapplication origination points 102; (ii) one or more content sources103, (iii) one or more application distribution servers 104; (iv) one ormore VOD servers 105, and (v) customer premises equipment (CPE) 106. Thedistribution server(s) 104, VOD servers 105 and CPE(s) 106 are connectedvia a bearer (e.g., HFC) network 101. A simple architecture comprisingone of each of the aforementioned components 102, 104, 105, 106 is shownin FIG. 1 for simplicity, although it will be recognized that comparablearchitectures with multiple origination points, distribution servers,VOD servers, and/or CPE devices (as well as different networktopologies) may be utilized consistent with the present disclosure. Forexample, the headend architecture of FIG. 1a (described in greaterdetail below), or others, may be used.

The data/application origination point 102 comprises any medium thatallows data and/or applications (such as a VOD-based or “Watch TV”application) to be transferred to a distribution server 104. This caninclude for example a third party data source, application vendorwebsite, CD-ROM, external network interface, mass storage device (e.g.,RAID system), etc. Such transference may be automatic, initiated uponthe occurrence of one or more specified events (such as the receipt of arequest packet or ACK), performed manually, or accomplished in anynumber of other modes readily recognized by those of ordinary skill. Theapplication distribution server 104 comprises a computer system wheresuch applications can enter the network system. Distribution servers arewell known in the networking arts, and accordingly not described furtherherein.

The VOD server 105 comprises a computer system where on-demand contentcan be received from one or more of the aforementioned data sources 102and enter the network system. These servers may generate the contentlocally, or alternatively act as a gateway or intermediary from adistant source.

The CPE 106 includes any equipment in the “customers' premises” (orother locations, whether local or remote to the distribution server 104)that can be accessed by a distribution server 104.

The VOD server 105 and application distribution servers 104 are a partof the headend architecture of the network 100. The headend 150 can beconnected to an internetwork (e.g., the Internet) 111.

Referring now to FIG. 1a , one exemplary embodiment of a headendarchitecture is described. As shown in FIG. 1a , the headendarchitecture 150 comprises typical headend components and servicesincluding billing module 152, subscriber management system (SMS) and CPEconfiguration management module 154, cable-modem termination system(CMTS) and OOB system 156, as well as LAN(s) 158, 160 placing thevarious components in data communication with one another. It will beappreciated that while a bar or bus LAN topology is illustrated, anynumber of other arrangements as previously referenced (e.g., ring, star,etc.) may be used consistent with the disclosure. It will also beappreciated that the headend configuration depicted in FIG. 1a ishigh-level, conceptual architecture, and that each MSO may have multipleheadends deployed using custom architectures.

The exemplary architecture 150 of FIG. 1a further includes a conditionalaccess system (CAS) 157 and a multiplexer-encrypter-modulator (MEM) 162coupled to the HFC network 101 adapted to process or condition contentfor transmission over the network. The distribution servers 164 arecoupled to the LAN 160, which provides access to the MEM 162 and network101 via one or more file servers 170. The VOD servers 105 are coupled tothe LAN 160 as well, although other architectures may be employed (suchas for example where the VOD servers are associated with a coreswitching device such as an 802.3z Gigabit Ethernet device). Aspreviously described, information is carried across multiple channels.Thus, the headend must be adapted to acquire the information for thecarried channels from various sources. Typically, the channels beingdelivered from the headend 150 to the CPE 106 (“downstream”) aremultiplexed together in the headend, as previously described and sent toneighborhood hubs (FIG. 1b ) via a variety of interposed networkcomponents.

It will also be recognized, however, that the multiplexing operation(s)need not necessarily occur at the headend 150 (e.g., in theaforementioned MEM 162). For example, in one variant, at least a portionof the multiplexing is conducted at a BSA switching node or hub (seediscussion of FIG. 1c provided subsequently herein). As yet anotheralternative, a multi-location or multi-stage approach can be used, suchas that described in U.S. Pat. No. 7,602,820, entitled “APPARATUS ANDMETHODS FOR MULTI-STAGE MULTIPLEXING IN A NETWORK” incorporated hereinby reference in its entirety, which discloses inter alia improvedmultiplexing apparatus and methods that allow such systems todynamically compensate for content (e.g., advertisements, promotions, orother programs) that is inserted at a downstream network node such as alocal hub, as well as “feed-back” and “feed forward” mechanisms fortransferring information between multiplexing stages.

Content (e.g., audio, video, data, files, etc.) is provided in eachdownstream (in-band) channel associated with the relevant service group.To communicate with the headend or intermediary node (e.g., hub server),the CPE 106 may use the out-of-band (OOB) or DOCSIS channels andassociated protocols. The OCAP 1.0, 2.0, 3.0 (and subsequent)specification provides for exemplary networking protocols bothdownstream and upstream, although the present disclosure is in no waylimited to these approaches.

“Switched” Networks—

FIG. 1c illustrates an exemplary “switched” network architecture. Whilea so-called “broadcast switched architecture” or BSA network isillustrated in this exemplary network architecture embodiment, it willbe recognized that the present disclosure is in no way limited to sucharchitectures.

Switching architectures allow improved efficiency of bandwidth use forordinary digital broadcast programs. Ideally, the subscriber is unawareof any difference between programs delivered using a switched networkand ordinary streaming broadcast delivery.

FIG. 1c shows the implementation details of one exemplary embodiment ofthis broadcast switched network architecture. Specifically, the headend150 contains switched broadcast control 190 and media path functions192; these element cooperating to control and feed, respectively,downstream or edge switching devices 194 at the hub site which are usedto selectively switch broadcast streams to various service groups. BSAmedia path 192 may include a staging processor 195, source programs, andbulk encryption in communication with a switch 275. A BSA server 196 isalso disposed at the hub site, and implements functions related toswitching and bandwidth conservation (in conjunction with a managemententity 198 disposed at the headend). An optical transport ring 197 isutilized to distribute the dense wave-division multiplexed (DWDM)optical signals to each hub in an efficient fashion.

Co-owned U.S. Patent Application Publication No. 2003/0056217 filed Sep.20, 2001 entitled “TECHNIQUE FOR EFFECTIVELY PROVIDING PROGRAM MATERIALIN A CABLE TELEVISION SYSTEM”, and issued as U.S. Pat. No. 8,713,623 onApr. 29, 2014, incorporated herein by reference in its entirety,describes one exemplary broadcast switched digital architecture,although it will be recognized by those of ordinary skill that otherapproaches and architectures may be substituted.

In addition to “broadcast” content (e.g., video programming), thesystems of FIGS. 1a and 1c (and 1 d discussed below) also deliverInternet data services using the Internet protocol (IP), although otherprotocols and transport mechanisms of the type well known in the digitalcommunication art may be substituted. One exemplary delivery paradigmcomprises delivering MPEG-based video content, with the videotransported to user PCs (or IP-based STBs) over the aforementionedDOCSIS channels comprising MPEG (or other video codec such as H.264 orAVC) over IP over MPEG. That is, the higher layer MPEG- or other encodedcontent is encapsulated using an IP protocol, which then utilizes anMPEG packetization of the type well known in the art for delivery overthe RF channels. In this fashion, a parallel delivery mode to the normalbroadcast delivery exists; i.e., delivery of video content both overtraditional downstream QAMs to the tuner of the user's STB or otherreceiver device for viewing on the television, and also as packetized IPdata over the DOCSIS QAMs to the user's PC or other IP-enabled devicevia the user's cable modem. Delivery in such packetized modes may beunicast, multicast, or broadcast.

Referring again to FIG. 1c , the IP packets associated with Internetservices are received by edge switch 194, and in one embodimentforwarded to the cable modem termination system (CMTS) 199. The CMTSexamines the packets, and forwards packets intended for the localnetwork to the edge switch 194. Other packets are discarded or routed toanother component.

The edge switch 194 forwards the packets receive from the CMTS 199 tothe QAM modulator 189, which transmits the packets on one or morephysical (QAM-modulated RF) channels to the CPE. The IP packets aretypically transmitted on RF channels (e.g., DOCSIS QAMs) that aredifferent that the RF channels used for the broadcast video and audioprogramming, although this is not a requirement. The CPE 106 are eachconfigured to monitor the particular assigned RF channel (such as via aport or socket ID/address, or other such mechanism) for IP packetsintended for the subscriber premises/address that they serve.

“Packetized Networks”—

While the foregoing network architectures described herein can (and infact do) carry packetized content (e.g., IP over MPEG for high-speeddata or Internet TV, MPEG2 packet content over QAM for MPTS, etc.), theyare often not optimized for such delivery. Hence, in accordance withanother embodiment of the disclosure, a “packet optimized” deliverynetwork is used for carriage of the packet content (e.g., IPTV content).FIG. 1d illustrates one exemplary implementation of such a network, inthe context of a 3GPP IMS (IP Multimedia Subsystem) network with commoncontrol plane and service delivery platform (SDP), as described inco-pending U.S. Provisional Patent Application Ser. No. 61/256,903 filedOct. 30, 2009 and entitled “METHODS AND APPARATUS FOR PACKETIZED CONTENTDELIVERY OVER A CONTENT DELIVERY NETWORK”, which is now published asU.S. Patent Application Publication No. 2011/0103374 of the same titlefiled on Apr. 21, 2010, each of which is incorporated herein byreference in its entirety. Such a network provides, inter alia,significant enhancements in terms of common control of differentservices, implementation and management of content delivery sessionsaccording to unicast or multicast models, etc.; however, it isappreciated that the various features of the present disclosure are inno way limited to this or any of the other foregoing architectures.

Referring now to FIG. 1e , another exemplary network architecture forthe delivery of packetized content disclosure useful with the presentdisclosure. In addition to on-demand and broadcast content (e.g., videoprogramming), the system of FIG. 1e may deliver Internet data servicesusing the Internet protocol (IP), although other protocols and transportmechanisms of the type well known in the digital communication art maybe substituted.

The network 1000 generally comprises a local headend 1001 incommunication with at least one hub 1003 via an optical ring 1007. Thedistribution hub 1003 is able to provide content to various userdevices, CPE 1022, and gateway devices 1020, via a network 1005.

Various content sources 1002 are used to provide content to a contentserver 1004. For example, content may be received from a local,regional, or network content library as discussed in co-owned U.S.application Ser. No. 12/841,906 filed on Jul. 22, 2010, entitled“APPARATUS AND METHODS FOR PACKETIZED CONTENT DELIVERY OVER ABANDWIDTH-EFFICIENT NETWORK”, and issued as U.S. Pat. No. 8,997,136 onMar. 31, 2015, which is incorporated herein by reference in itsentirety. Alternatively, content may be received from linear analog ordigital feeds, as well as third party content sources. Internet contentsources 1010 (such as e.g., a web server) provide internet content to apacketized content server 1006. Other IP content may also be received atthe packetized content server 1006, such as voice over IP (VoIP) and/orIPTV content. Content may also be received from subscriber andnon-subscriber devices (e.g., a PC or smartphone-originated user madevideo). In one embodiment, the functionality of both the content server1004 and packetized content server 1006 may be integrated into a singleserver entity.

A central media server located in the headend 1001 may be used as aninstalled backup to the hub media servers as (i) the primary source forlower demand services, and (ii) as the source of the real time,centrally encoded programs with PVR (personal video recorder)capabilities. By distributing the servers to the hub stations 1003 asshown in FIG. 1e , the size of the fiber transport network associatedwith delivering VOD services from the central headend media server isadvantageously reduced. Hence, each user has access to several serverports located on at least two servers. Multiple paths and channels areavailable for content and data distribution to each user, assuring highsystem reliability and enhanced asset availability. Substantial costbenefits are derived from the reduced need for a large contentdistribution network, and the reduced storage capacity requirements forhub servers (by virtue of the hub servers having to store and distributeless content).

It will also be recognized that a heterogeneous or mixed server approachcan be utilized consistent with the disclosure. For example, one serverconfiguration or architecture may be used for servicing cable,satellite, HFCu, etc. subscriber CPE-based session requests, while adifferent configuration or architecture may be used for servicing mobileclient requests. Similarly, the content servers 1004, 1006 can either besingle-purpose/dedicated (e.g., where a given server is dedicated onlyto servicing certain types of requests), or alternatively multi-purpose(e.g., where a given server is capable of servicing requests fromdifferent sources).

The network 1000 of FIG. 1e may further include a legacymultiplexer/encrypter/modulator (MEM; not shown) coupled to the network1005 adapted to “condition” content for transmission over the network.In the present context, the content server 1004 and packetized contentserver 1006 may be coupled to the aforementioned LAN, thereby providingaccess to the MEM and network 1005 via one or more file servers (notshown). The content server 1004 and packetized content server 1006 arecoupled via the LAN to a headend switching device 1008 such as an 802.3zGigabit Ethernet (or incipient “10G”) device. Video and audio content ismultiplexed at the headend 1001 and transmitted to the edge switchdevice 1012 (which may also comprise an 802.3z Gigabit Ethernet device).

In one exemplary delivery paradigm MPEG-based video content may bedelivered, with the video transported to user PCs (or IP-based CPE) overthe relevant transport (e.g., DOCSIS channels) comprising MPEG (or othervideo codec such as H.264 or AVC) over IP over MPEG. That is, the higherlayer MPEG- or other encoded content may be encapsulated using an IPprotocol, which then utilizes an MPEG packetization of the type wellknown in the art for delivery over the RF channels or other transport,such as via a multiplexed transport stream (MPTS). In this fashion, aparallel delivery mode to the normal broadcast delivery exists; e.g., inthe cable paradigm, delivery of video content both over traditionaldownstream QAMs to the tuner of the user's STB or other receiver devicefor viewing on the television, and also as packetized IP data over theDOCSIS QAMs to the user's PC or other IP-enabled device via the user'scable modem. Delivery in such packetized modes may be unicast,multicast, or broadcast. Delivery of the IP-encapsulated data may alsooccur over the non-DOCSIS QAMs.

Individual CPEs 1022 of the implementation of FIG. 1e may be configuredto monitor the particular assigned RF channel (such as via a port orsocket ID/address, or other such mechanism) for IP packets intended forthe subscriber premises/address that they serve.

In the switched digital variant, the IP packets associated with Internetservices are received by edge switch, and forwarded to the cable modemtermination system (CMTS) 1016. The CMTS examines the packets, andforwards packets intended for the local network to the edge switch.Other packets are in one variant discarded or routed to anothercomponent.

The edge switch forwards the packets receive from the CMTS to the QAMmodulator, which transmits the packets on one or more physical(QAM-modulated RF) channels to the CPE. The IP packets are typicallytransmitted on RF channels that are different than the RF channels usedfor the broadcast video and audio programming, although this is not arequirement. As noted above, the CPE are each configured to monitor theparticular assigned RF channel (such as via a port or socket ID/address,or other such mechanism) for IP packets intended for the subscriberpremises/address that they serve.

In one embodiment, both IP data content and IP-packetized audio/videocontent is delivered to a user via one or more universal edge QAMdevices 1018. According to this embodiment, all of the content isdelivered on DOCSIS channels, which are received by a premises gateway1020 (described subsequently herein) and distributed to one or more CPE1022 in communication therewith. Alternatively, the CPE 1022 may beconfigured to receive IP content directly without need of the gateway orother intermediary. As a complementary or back-up mechanism, audio/videocontent may also be provided in downstream (in-band) channels asdiscussed above; i.e., via traditional “video” in-band QAMs. In thisfashion, a co-enabled digital set top box (DSTB) or other CPE couldreadily tune to the new (in-band) RF video QAM in the event that theirIP session over the DOCSIS QAM is for some reason interrupted. This mayeven be accomplished via appropriate logic within the CPE (e.g.,autonomously, or based on signaling received from the headend or otherupstream entity, or even at direction of a user in the premises; e.g.,by selecting an appropriate DSTB or other CPE function).

In the embodiment illustrated in FIG. 1e , IP packetized content isprovided to various user devices via the network 1005. For example,content may be delivered to a gateway apparatus 1020 which distributescontent received thereat to one or more CPE 1022 in communication withthe apparatus 1020.

In another variant, elements in both the headend and CPE 1022 arespecially adapted to utilize transmission infrastructure to transmit andreceive both multiplexed wideband content and legacy content as isdescribed in co-owned U.S. patent application Ser. No. 11/013,671 filedon Dec. 15, 2004, entitled “METHODS AND APPARATUS FOR WIDEBANDDISTRIBUTION OF CONTENT”, and issued as U.S. Pat. No. 8,015,306 on Sep.6, 2013, which is incorporated by referenced herein in its entirety. Asdiscussed therein, the CPE 1022 or gateway 1020 of this embodiment maybe configured to contain multiple tuners (or a single wide-band tuner)which allow the device to receive the signals from all of the relevantphysical carriers simultaneously. The carriers are demodulated, andchannel-based decryption and basic demultiplexing (recombination) isperformed. If multiplexed, the streams are then delivered to a transportdemultiplexer which demultiplexes all of the streams resident within thestatistical multiplex.

Methods and apparatus for the switched delivery of content may also beutilized consistent with the present disclosure. For example, only thatcontent for which there is at least one request from a user device maybe provided. In one embodiment, the methods and apparatus disclosed inco-owned U.S. patent application Ser. No. 09/956,688 entitled “TECHNIQUEFOR EFFECTIVELY PROVIDING PROGRAM MATERIAL IN A CABLE TELEVISIONSYSTEM”, filed on Sep. 20, 2001, and issued as U.S. Pat. No. 8,713,623on Apr. 29, 2014, which is incorporated herein by reference in itsentirety, may be utilized for providing “switched” delivery of the IPcontent. For example, a mechanism may be employed whereby the deliveryof a session is based at least in part on logic to determine whether anyusers for the session are active; e.g., a multicast with no remaining“viewers” (or session participants) may be collapsed, and the bandwidthreclaimed.

In another variant, IP simulcast content and existing on-demand, voice,and broadcast content are all provided to the headend switch device 1008of FIG. 1e . The headend switch 1008 then provides the content to theoptical ring 1007 for provision to one or more distribution hubs 1003.IP simulcast content is in one exemplary implementation retrieved from aplurality of content sources at an IPTV server.

The IP-packet content is transmitted to subscriber devices via theuniversal edge QAM 1018 and the edge network 1005. The IP video(“simulcast”) content is presented to client devices capable ofreceiving content over the DOCSIS QAMs. For example, the aforementionedgateway device 1020 (as well as an advanced CPE 1022 such as anIP-enabled DSTB may receive the IP simulcast. Legacy CPE may receivecontent via the gateway device 1020, or via an audio/video “back-up”MPEG transport stream as previously described.

It is further appreciated that content may be delivered to variousWorldwide Interoperability for Microwave Access (WiMAX)-enabled mobiledevices (e.g., PMD or non-legacy CPE) via a WiMAX distribution hub ofthe type now ubiquitous in the wireless arts. WiMAX is a wirelesstechnology that provides high-throughput broadband connections overlonger distances (as compared to short-range technologies such as WLAN,Bluetooth or PAN). WiMAX can be used for a number of applications,including “last mile” broadband connections, cellular backhaul, hotspotcoverage, and high-speed enterprise connectivity, as well as broadbanddelivery to mobile devices.

Moreover, the aforementioned WiMAX technology may be used in conjunctionwith a WiMAX-enabled gateway (not shown) or CPE, such that content isdelivered wirelessly to the gateway or CPE from the distribution hub,irrespective of the indigenous wired or optical distribution networkinfrastructure.

In the illustrated embodiment, the gateway device 1020 serves as agateway to the IP content for other client devices (such as other CPE1022 and PMD). The gateway device 1020 may communicate with one or moreconnected CPE 1022, as well as utilize Wi-Fi capabilities (where soequipped) to communicate wirelessly to other devices. It will also berecognized that the present disclosure may be configured with one ormore short-range wireless links such as Bluetooth for lower bandwidthapplications (or UWB/PAN for greater bandwidth applications).

In another embodiment, content received at a first user CPE 1022 may betransmitted to CPE 1022 of other premises in a peer-to-peer (P2P)fashion. For example, first content may be requested and received at afirst CPE 1022. Then, when a second CPE 1022 in the same region ordivision requests the same content, the request may be examined by aheadend entity (not shown), or the gateway 1020 acting as a peer proxy,to determine that the requesting second device CPE 1022 is entitled toreceive the content and that the content is available at the first CPE1022. The headend entity directs a peer-to-peer communication to beestablished between the authorized second CPE 1022 and the CPE 1022having the requested content. It is appreciated that while describedherein in the context of a single CPE 1022 providing content to a secondCPE 1022, several CPE 1022 having the content thereon may be contactedfor simultaneous delivery of the content to one or more second CPE 1022.In one such implementation, the peer-to-peer communication methods andapparatus disclosed in co-owned U.S. patent application Ser. No.11/726,095 entitled “METHOD AND APPARATUS FOR CONTENT DELIVERY ANDREPLACEMENT IN A NETWORK” filed Mar. 20, 2007, which is incorporatedherein by reference in its entirety, may be utilized in conjunction withthe present disclosure. As discussed therein, these P2P methods andapparatus also advantageously improve the “robustness” or capability ofthe network with respect to ensuring that subscribers or other users canreceive and access desired content when they want, as well as seamlesslyrepairing or reconstituting damaged or missed portions of that content(including even an entire streamed program, broadcast or download).

It is still further appreciated that the delivery of content may includedelivery from an “off-net” distribution hub (not shown) to anothernetwork (not shown), not associated with the MSO. In this embodiment, arequesting device (such as CPE 1022 or gateway 1020) may request contentfrom a local headend 1001 which is transferred over both MSO-maintained(“on-net”) and “off-net” networks advantageously.

“Anycast” Content Delivery Networks—

FIG. 2 illustrates an exemplary anycast network configuration fordelivery of packetized content in accordance with one or moreimplementations of the present disclosure. It will be appreciated thatthe configuration 200 shown in FIG. 2 is a high-level logicalrepresentation which can be adapted for use with, inter alia, one ormore of the foregoing network architectures described with respect toFIGS. 1a-1e herein, or yet other architectures.

The network configuration 200 includes a content delivery network 210operably coupled to one or more clients 202, 204, 206. In someimplementations, individual clients (e.g., 202) include for instance theCPE 1022 described above with respect to FIG. 1e . The CDN 210 maycomprise multiple content delivery sources, e.g., servers 212, 214, 216.In some implementations, the anycast approach includes a source address(e.g., IP address of content servers 212, 214, 216) numberingmethodology, wherein a given IP addresses, e.g., 10.2.2.1, may beassociated with multiple content servers providing given content and/orservice. Individual servers 212, 214, 216 with the same IP address aredisposed in geographically diverse locations. The anycast approachfurther comprises, in various embodiments, the advertisement of deliveryroutes. The routes 222, 224, 226 are advertised in the routing tables.The tables are available at each serving location (e.g., servers 212,214, 216) so as to enable the “shortest path” routing of requests fromclients (e.g., 206) to the closest destination server (e.g., 216) viathe shortest route 226 based on normal IP routing rules. Hence, theanycast methodology advantageously enables abstraction of the contentavailability advertisement from the actual serving of content. Suchabstraction can, inter alia, alleviate a need for a centralized controlsystem, such as those of the prior art.

FIG. 2 depicts three (3) distinct clients 202, 204, 206 that may attemptto reach a content server at address 10.2.2.1. By employing the anycastmethodology of the present disclosure, individual clients 202, 204, 206may be routed to three distinct servers 212, 214, 216, via routes 222,224, 226. The routes 222, 224, 226 can be configured in accordance withone or more IP routing rules. In some implementations, the routing ruleis based on proximity of a content server to the client (e.g., route the226 for the client 206 and the server 216). The routing rule may also beconfigured based on server availability, server load, delivery cost,route available bandwidth, subscription level (e.g., basic or guaranteeddelivered bandwidth) and/or other metrics or combinations thereof.

In the exemplary realization illustrated in FIG. 2, content delivery maybe configured as follows. To receive content, a client device (e.g.,202) may submit a request to a CST (or content location mapping layer).The request may comprise a request for a particular content (e.g., watcha TV show) and/or a service (e.g., a video services (e.g., network DVR,second screen apps, cloud based digital navigators, OnDemand orover-the-top (OTT) content (e.g., Netflix®, Hulu®, virtual MSO services,etc.)), visual communications (e.g., Skype®, Facetime®, etc), or cloudcomputing/storage/streaming and/or other services. The CST provides theclient with a universal resource locator (URL) (e.g.timewarner.video.com) associated with the content and/or service beingrequested. The client may resolve the hostname in that URL to adestination IP address (e.g., 10.2.2.1) of one or of one or more serversthat is to provide the requested content. In some implementations, theclient may perform a DNS lookup to resolve the host name. The client mayalso or alternatively be provided with a list of servers based login andauthentication into the network. In some implementations, based on a DNSrequest by the client, the DNS server may respond with a list ofavailable IP addresses, e.g., 10.0.0.19, 10.0.0.20, 10.0.0.1, 10.0.0.2.The client may be configured to select one address using one or moreselection methodologies such as e.g., random selection, and/or othermechanism. In some implementations, the DNS server may provide an IPaddress (e.g., 10.2.2.1) from a bank of available IP addresses using,e.g., round robin or other selection methodology. The variousimplementations described above can advantageously enable spreading ofload associated with content delivery among a number (N) of IP addressesin the pool.

The client 206 can submit requests for content and/or service to theresolved address (10.2.2.1). Based on the anycast methodology describedabove, a server associated with the selected route (e.g., the route 226to the closes server 216) serves the requested content. It will beappreciated by those skilled in the art that although DNS addressresolution is described above, other IP distribution/resolutionmethodologies may be utilized, such as, e.g., provision of a server namelist during client authentication with the network.

IP distribution/resolution methodologies may also utilize an arbitrationlayer, which receives the resolution request (be it DNS, or otherwise)and either locally select an edge server, or proxy the request toanother selecting agent (Velocix DNS, for example).

Various portions of the CDN may become unavailable due to failures, highdemand, and/or maintenance. FIG. 3 illustrates an exemplary routeadvertisement and client flow configuration that implements redundancyfor a content delivery network in accordance with one or moreimplementations. Content delivery redundancy may be effectuated by useof content delivery caches. The exemplary network configuration 300includes a content delivery network 310 operably coupled to one or moreclients 304, 306, 302. The CDN 310 also includes one or more contentdelivery caches 312, 314, 316. To account for equipment failure and/orallow for dynamic traffic adjustment, a routing protocol is implementedbetween the delivery cache (e.g., 312, 314, 316 in FIG. 3) and therespective upstream router (e.g., 332, 334, 336). In someimplementations, the delivery cache(s) may advertise a number of theanycast routes (between 0 and N) that the clients may receive thecontent from. A failure of a given delivery cache and/or route canaccordingly be detected, and “converged around”.

The arrows denoted 342, 344, 346 in FIG. 3 correspond to border gatewayprotocol (BGP) route advertisements; arrows denoted 322, 324, 326correspond to the content requests and fulfillment. Clients of thenetwork system shown in FIG. 3 have already performed cache resolutionstep using e.g. DNS. In one embodiment, the cache resolution providesclients 302, 304, 306 with two IP addresses 10.0.0.1 and 10.0.0.2associated with the caches 312, 314, 316. The cache 312 is in theexemplar of FIG. 3 configured to serve content via the IP address10.0.0.1; the caches 314, 316 are configured to serve content via the IPaddresses 10.0.0.1 and 10.0.0.2. The client 302 and the client 304 mayselect the address 10.0.0.2 for content requests and fulfillment; theclient 306 may select the address 10.0.0.1. Responsive to a detection ofa failure, the delivery cache 312 removes its route from the advertisedroutes. In some implementations, the cache 312 route removal may beeffectuated by discontinuing of IP address 10.0.0.1 advertisement.

The failure referenced above may be due to any number of reasons (orcombinations thereof), such as e.g., excessive load, hardware failure,and/or maintenance.

It is noteworthy that the exemplary anycast approach described hereinmay enable the caches 314, 316 may continue advertising the route10.0.0.1. The clients 306, 304 can select routes 326, 324, respectively,to the geographically closest cache. The client 302 selects the route322 to the geographically closest of the available caches (e.g., thecache 316) via the address 10.0.0.2, as the geographically closest cache312 to the client 302 is not available.

It is also appreciated that the cache selection/deactivation mechanismdescribed herein may enable cache load manipulation (e.g., decrease orincrease). In some implementations, other BGP route selection criteriamay also be used for cache activation/deactivation, e.g., transmissioncost, route available bandwidth, subscription level of a client, and/orother metrics.

The “anycast” CDN described herein may be configured to reduce (and evenaltogether prevent) load oscillation due to two occurrences of one ormore non-responsive entities (e.g., caches) within the network. Theaddress advertising block of the anycast CDN may be configured inaccordance with e.g., a mechanism which achieves a desired performancegoal, such as for example an exponential hold-down mechanism. Thehold-down mechanism may in one variant increasingly delay the amount oftime the broadcast entity (e.g., a delivery cache) may wait beforeadvertising available IP addresses and/or withdrawing an availableroute.

In one or more implementations, the CDN includes a load balancingalgorithm or apparatus configured to diagnose and/or mitigate cascadingload-based problems and/or uncontrolled load oscillations that mayoccur.

In some instances of content availability advertisement via BGPannouncements, hierarchical caching may be supported through the use ofdifferent pools of IP addresses advertised using the exemplary anycastmethodology described herein. FIG. 4 depicts an exemplar of hierarchicalcaching in a content delivery network configured in accordance with oneor more implementations of the present disclosure. The networkconfiguration 400 of FIG. 4 includes a content delivery network 410operably coupled to one or more clients 402, 404, 406 (e.g., the CPE1022 of FIG. 1e ). One or more caches (e.g., 412) function as a deliverycache. The delivery cache 412 is in one embodiment characterized by anaccess link to a content server (e.g., 430 in FIG. 4). One or morecaches (e.g., 414) include tier 1 hierarchical cache. The tier 1hierarchical cache 414 is coupled to the delivery cache 412. The tier 1hierarchical cache 414 can be characterized by a route to a client406_comprising a single hop (e.g., the route 424 of FIG. 4). One or morecaches (e.g., 414) are tier 1 hierarchical caches, and are coupled tothe delivery cache 412.

In the network configuration 400 of FIG. 4, the client 402 can beconfigured to receive content from the cache 412 via a delivery route422. Likewise, the client 404 receives content from the cache 412 viathe delivery route 420. The delivery cache 412 can be configured toprovide the content by advertising, e.g., IP address 10.0.0.1. Thedelivery cache 412 is further configured to use addresses10.0.0.8-10.0.0.29 to communicate to one or more second tier caches(e.g., 414 in FIG. 4). In some realizations, the content requested bythe client 402 may have been previously requested by one or more otherentities of the network 400 (e.g., the client 406). This content may bedeemed as ‘popular’, and retained (stored) by the cache 414 for fasterfulfillment of future requests. The use of second and/or third tiercaches advantageously reduces content retrieval from a content server(e.g., 1004 in FIG. 1e ). The use of caching reduces delays and/ortraffic loads associated with serving content to network clients (e.g.,402, 404, 406) as well.

By way of a non-limiting example, the cache 412 utilizes a second tiercache 414 to retrieve (backfill) cached content for the route 422; thecontent being requested by the client 404 may be deemed less popular(e.g., compared to the content being requested by the client 402), andmay be available from the third tier cache (416). The cache 412 utilizesthe third tier cache 416 in order to fulfill content requests for theroute 420. The cache 412 utilizes the address 10.0.0.16-10.0.0.29 inorder to retrieve the content (that may be associated with the route420) from the cache 416. The routing of a content request (by, e.g., theclient 414) from the first tier cache 412 to the third tier cache 416 isreferred to as cache tier “skipping”. The cache hierarchy may comprise anumber of layers that may be supported by the network hardware and/orsoftware.

In some implementations, the second tier cache 414 may advertise theaddress 10.0.0.1, thereby enabling direct service of client requests. Asshown in FIG. 4, the client 406 may utilized the cache 414 in order toreceive content via the route 424. With respect to the client 406, thecache 414 is referred to as the “first tier cache”. BGP announcements440, 444, 446 may be communicated to respective routers 432, 434, 436 toaccomplish the foregoing.

In the exemplary implementation, the first tier (delivery) cache (e.g.,412) is configured to service client requests by advertising an addressfrom the range between 10.0.0.0 and 10.0.0.29. A second tier cache(e.g., 414) is configured to advertise an address from the range between10.0.0.8 and 10.0.0.29. A third tier cache (e.g., 416) is configured toadvertise an address from the range between 10.0.0.16 and 10.0.0.29.

Proxy-enabled servers can also be configured to select a backfill sourcebased on the path being requested. This method also allows for ahierarchical cache to also serve as a client-facing cache by advertisingone or more routes out of the 10.0.0.0-10.0.0.29 pool. Address basedrouting may allow skipping of cache tiers, backfilling to a tier morethan 1 layer higher. In some implementations, the backfill iseffectuated from the content origin (e.g., the content server 1004 inFIG. 1e ). By way of an illustration, requests from the client 402requesting content associated with, e.g., the address 10.0.0.10 may berouted to the second tier cache 414. Requests from the client 402requesting content associated with, e.g., the address 10.0.0.20 may berouted to the third tier cache 416. Clients would be given addresses outof the range according to 10.0.0.0/27, while client facing deliverycaches would be configured to backfill from the range according to10.0.0.8/29.

As a brief aside, so-called “bit mask” or “slash” notation is commonlyused within the networking arts to represent a range of addressesbetween a highest address and a lowest address. Bit mask notationconsists of the lowest address which is appended with the number of mostsignificant bits to be “masked off” (the most significant bits for thehighest address which are the same as the most significant bits of thelowest address can be ignored). Another common notation is the so-called“IP subnet mask” notation which is a decimal (i.e., base 10)representation of each byte of an IP address that is to be masked e.g.,an IP subnet mask of 255.255.255.224 masks the 27 most significant bitsof an IP address. In the foregoing example, the range from 10.0.0.29 to10.0.0.0 requires 5 bits to express (29#decimal is equivalent to11101#binary). Thus, the range of addresses can be represented with thebit mask notation of 10.0.0.0/27 which indicates a lowest address of10.0.0.0, and where the 27 most significant bits are the same betweenthe highest and lowest address of the range (i.e., 32 bits of totaladdress minus the 27 most significant bits results in the 5 bitsnecessary to represent the range).

FIG. 5 depicts an exemplary VOD pre-seeding configuration 500 in ananycast CDN 510 in accordance with one or more implementations of thepresent disclosure. The network configuration 500 of FIG. 5 includes acontent delivery network 510 operably coupled to one or more clients502, 504 (e.g., the CPE 1022 of FIG. 1e ). One or more caches (e.g.,512) function as a delivery cache. The delivery cache is in oneembodiment characterized by an access link to a content origin (e.g.,server 516 in FIG. 5). One or more caches (e.g., 514) include tier 1hierarchical cache. The tier 1 hierarchical cache 514 is coupled to thedelivery cache 512.

In the network configuration 500 of FIG. 5, the clients 502, 504 can beconfigured to receive content from the cache 512. The delivery cache 512can be configured to provide the content by advertising, e.g., IPaddress 10.0.0.1. The clients 502, 504 may request the desired contentusing the exemplary anycast methodology, via e.g., the IP address10.0.0.1.

A salient feature of the “anycast” approach described herein is thatpopular VOD content can be pre-seeded on client delivery caches,allowing the clients to pull content from these assets without thepenalty of a first-request backfill. Pre-seeding, in conjunction with“VOD pool” address advertisement, may be configured to direct a client(e.g., the client 504 in FIG. 5) to the closest client delivery cache(e.g., 512) that may already contain the requested content. The contentassociated with the IP address 10.0.0.1 may be provided to the deliverycache 512 from the content origin 516 via the route 526. Accordingly,the pre-seeded content delivery may be accomplished via a single hoproute (e.g., 520, 522 in FIG. 5). Responsive on the requested contentbeing absent (e.g., not pre-seeded), the client delivery cache 512 mayperform backfill steps. In some implementations, the backfill maycomprise requesting the non-pre-seeded content (e.g., associated withthe IP address 10.0.0.8/29) from the tier 1 cache 514. Non-pre-seededcontent delivery may be accomplished via a route comprising two or morehops (e.g., 520 and 528 or 522 and 528 in FIG. 5).

Methods—

FIGS. 6-8 illustrate methods of content provision using anycast CDNmethodology of the disclosure in accordance with one or more exemplaryimplementations. The operations of methods 600, 700, 800 presented beloware merely intended to be illustrative of the broader principles. Insome implementations, methods 600, 700, 800 may be accomplished with oneor more additional operations not described, and/or without one or moreof the operations discussed. Additionally, the order in which the stepsof methods 600, 700, 800 are illustrated in FIGS. 6-8 described below isnot intended to be limiting.

The methods 600, 700, 800 may be implemented for example usingcomputerized apparatus and logic; e.g., in one or more processingdevices (e.g., a digital processor, an analog processor, a digitalcircuit designed to process information, an analog circuit designed toprocess information, a state machine, and/or other mechanisms forelectronically processing information and/or execute computer programmodules). The one or more processing devices may include one or moredevices executing some or all of the operations of methods 600, 700, 800in response to instructions stored electronically on an electronicstorage medium. The one or more processing devices may include one ormore devices configured through hardware, firmware, and/or software tobe specifically designed for execution of one or more of the operationsof methods 600, 700, 800.

Referring to FIG. 6, an exemplary embodiment of a method 600 for contentdelivery in a packetized network using anycast CDN is illustrated. Atstep 602 of method 600, one or more addressees may be assigned tocontent and/or service. In some implementations, the address 10.2.2.1may be assigned to, e.g., a discovery channel, an interactiveapplication (e.g., multiuser video game), and/or an audio-visualcommunications application (e.g., Skype®).

At step 604 of the method 600, the one or more IP addresses areassociated with multiple nodes of the packetized network. In someimplementations, individual nodes may comprise delivery cache 214 inFIG. 2 and/or a hierarchical cache (e.g., 414 in FIG. 4). Individualnodes may be disposed locally, and/or in geographically diverselocations (e.g., different buildings, cities, counties, and/or otherlocations) in accordance with a demand map associated with networkclients.

At step 606, a pool of routes to the IP address for the content areadvertised. In some implementations, the address advertising isperformed in accordance with the anycast methodology, and comprisesplacing the advertised routes into the routing tables associated withindividual nodes and/or locations.

At step 608, a route to a destination server is determined using e.g., adelivery rule. In some implementations, the rule may comprise a‘shortest path’ routing rule, and the destination node may be thegeographically closest node. As will be appreciated by those of ordinaryskill given this disclosure, various other rules may be utilized withthe methodology described herein, such as, for example, lowest delayroute, route based on availability, guaranteed bandwidth, and/or otherrules.

FIG. 7 illustrates an exemplary embodiment of a method for contentretrieval by a client of anycast CDN in accordance with the disclosure.

At step 702 of the method 700, the client submits a request. The requestmay comprise for instance a request for content (e.g., VOD), anapplication, and/or a service (e.g., visual communications).

At step 704, the client receives a hostname (e.g., a URL) associatedwith the requested content (e.g., timewarnervideo.new.com).

At step 706, the destination hostname is resolved to determine an IPaddress associated with the content. In some implementations, the clientperforms a DNS lookup to resolve the host name. The client may be forinstance provided with a list of servers for login and authenticationinto the network. Based on a DNS request by the client, the DNS servercan respond with a list of available IP addresses, e.g., 10.0.0.19,10.0.0.20, 10.0.0.1, 10.0.0.2.

At step 708, the client obtains a route to the destination node inaccordance with a routing rule. In some implementations, the nodecomprises a delivery cache (e.g., cache 214 in FIG. 2) and/or ahierarchical cache (e.g., 414 in FIG. 4). The client is in oneembodiment configured to select one address using one or more selectionmethodologies, such as e.g., random selection, incrementing/decrementingselection, and/or other mechanism. The DNS server provides an IP address(e.g., 10.2.2.1) from a bank of available IP addresses using, e.g.,round-robin selection methodology. The approaches described aboveadvantageously enable spreading of load associated with content deliveryamong N IP addresses in the pool. In one embodiment, the routing rule isconfigured based on one or more of: (i) geographical proximity of theclient to the node, (ii) lowest delay route, (iii) route based onavailability, (iv) guaranteed bandwidth, (v) content encoding level(e.g., MPEG2, MPEG4), (vi) client device type (e.g., a smartphone, atelevision), (vii) client connection bandwidth (e.g., LTE, Wi-Fi),and/or (viii) client subscription level.

At step 710, the content may be received by the client from the node viathe route. In some implementations, content provision is a single hopdelivery from a delivery cache (e.g., 212 in FIG. 2), and/or a multi-hopdelivery from a higher tier cache (e.g., 414 in FIG. 4) of the networkcache hierarchy, e.g., as described in detail with respect to FIG. 8,below.

FIG. 8 illustrates an exemplary embodiment of a method for contentprovision in anycast CDN comprising hierarchical cache in accordancewith the disclosure.

At step 802 of the method 800, a request is received by the network. Therequest comprises for example a request for an advertised content (e.g.,VOD), an application, and/or a service (e.g., visual communications).The content is associated with a pool of advertised addresses (e.g.,10.0.0.0-10.0.0.29).

At step 804, the request is routed to a delivery cache using, forexample the closest route rule.

At step 806 a determination is made as to whether the requested contentis available at the cache. Responsive to a determination that thecontent is available, the method proceeds to step 808, wherein thecontent is provided to the client. Content provision of operation 808comprises a single hop delivery from a delivery cache (e.g., 212 in FIG.2) and/or a multi-hop delivery from a higher tier cache (e.g., 414 inFIG. 4 having the IP address pool 10.0.0.8-10.0.0.29 associatedtherewith) of the network cache hierarchy.

Responsive to a determination at step 806 that the requested content isnot available, the method proceeds to step 810. At step 810, adetermination is made as to whether additional tiers of the cachehierarchy may be accessed. In one example, the delivery cache isconfigured with a list of IP addresses for higher-tier caches that areable to fulfill the backfill request. In one or more implementations,the cache tier availability is based on a response from a higher levelnode within the cache hierarchy (e.g., 10.0.0.28).

Responsive to a determination at step 810 that another level of cachemay be accessed, the method proceeds to step 812. At step 812, therequest may be routed to the next tier cache (e.g., tier 1 cache 414 ofFIG. 4). Subsequently, the method may proceed to step 806.

Exemplary Node Apparatus—

The exemplary embodiments of the anycast CDN described herein may beimplemented using general purpose software and/or hardware resources.For example, the software may comprise a Linux operating system (OS)based delivery cache application running a routing daemon (e.g., aQuagga routing suite), a caching daemon, and/or a route manager. Theroute manager may be configured to advertise and/or withdraw deliveryroutes based on one or more metrics described herein.

Hardware resources can include for example general-purpose computinghardware. FIG. 9 depicts an exemplary embodiment of a node apparatus ofa packetized network useful for providing content using the anycastmethodology described herein. The node 900 includes processing logic 902(e.g., a processor) configured to execute one or more software modules,a memory 904 to support application execution, storage 910, and one ormore interfaces 906. The interfaces 906 include one or more networkinterfaces for communication to an origin server 430, cache tiers 416 inFIG. 4, clients 402, and/or other network entities. The memory 904 maybe utilized for storing application data and/or caching content. Thestorage can be utilized for storing content, routing tables, operationsystem data (e.g., OS image), and/or other data. The memory 904 in onevariant is characterized by lower access time, compared to the storage910, the latter which comprises a nonvolatile medium (e.g., magnetic,optical, and/or charge based (e.g., flash), while the memory 904 maycomprise a volatile medium (e.g., DRAM, SRAM, and/or other).

In one or more implementations, the node 900 is configured usingcommercial off-the-shelf computing platform (e.g., Dell PowerEdgeserver, and/or another apparatus), which advantageously obviates theneed for custom or specialized hardware. Hardware and/or softwareconfigurations of individual nodes (e.g., 412, 414, 416) may be set inaccordance with requirements of a target application (e.g., contenttraffic). By way of a non-limiting illustration, a VOD traffic node maybe configured to comprise larger storage 910 compared to a nodeconfigured to serve linear content. The latter node may include more offaster access memory 904, as compared to the VOD node. In someimplementations, the network has a heterogeneous configuration, whereinthe hardware configuration of individual nodes is tailored in accordancewith specific cost and/or performance requirements. Software “agnostic”implementations of the CDN described herein advantageously enableoptimization of software modules (e.g., web server) for the trafficbeing served. By way of example, an Apache server may be selected tohandle linear content, and a NGiNX server may be selected for providingVOD content.

In some implementations, a given hardware node configuration configured,e.g., to support linear content delivery, is augmented to support VOD byuse of additional storage (e.g., hard disks). The additional storage canbe embodied within the node serve, and/or as an attached array (e.g.,via a serial bus and/or as network attached storage).

Exemplary Operation—

In the exemplary configuration illustrated in FIG. 2, content deliverymay be configured as follows. To receive content, a client device (e.g.,device 202) may submit a request to a CST (or content location mappinglayer). The request may be for instance a request for a particularcontent (e.g., watch a TV show) and/or a service, (e.g., a videoservices (e.g., network DVR, second screen apps, cloud based digitalnavigators, OnDemand or over-the-top (OTT) content (e.g., Netflix®,Hulu®, virtual MSO services, and/or other)), visual communications(e.g., Skype®, Facetime®, and/or other), or cloudcomputing/storage/streaming and/or other services. The CST may providethe client with a universal resource locator (URL) (e.g.timewarner.video.com) of a server that may be providing the contentand/or service requested. The client resolves the hostname in that URLto a destination IP address (e.g., 10.2.2.1). The client performs a DNSlookup to complete this step. In some implementations, based on a DNSrequest by the client, the DNS server responds with a list of availableIP addresses, e.g., 10.0.0.19, 10.0.0.20, 10.0.0.1, 10.0.0.2. The clientselects one address using one or more selection methodologies such asvia a random selection or selection of addresses not previouslyselected. The DNS server provides an IP address (e.g., 10.2.2.1) from abank of available IP addresses using, e.g., round robin selectionmethodology. As previously described, the foregoing approach enablesspreading of load associated with content delivery among N IP addressesin the pool.

The client 206 submits requests for content and/or service to theresolved address (10.2.2.1). Based on the anycast methodologiesdescribed above, a server associated with the selected route (e.g., theroute 226 to the closes server 216) serves the requested content. Itwill be appreciated by those skilled in the art that although DNSaddress resolution is described above, other IP distribution/resolutionmethodologies may be utilized, such as, offering of IP addresses duringthe content mapping step, rather than a URL. IP distribution/resolutionmethodologies may for example utilize an arbitration layer, which wouldreceive the resolution request (be it DNS or otherwise), and eitherlocally select an edge server, or proxy the request to another selectingagent (Velocix DNS, for example).

The anycast CDN framework may be utilized with the transmission controlprotocol (TCP). In some implementations, a TCP session is expected notto exceed a given duration (e.g., 0.5 second to 1 second). By way of anon-limiting illustration, when the duration of the TCP session isconfigured less than 1 s, probability of changes to networkconfiguration (e.g., route withdrawals and/or changes) is reduced,compared to a longer session duration (e.g., 10 s). Even when a networkchange occurs within an active TCP session, the impact of the change maybe smaller (compared to a longer session duration), as shorter TCPsessions may deliver less data (and may in some instances need to havethe data re-requested). Responsive to change detection during an activeTCP session, a new session may be established in accordance with thechanged network configuration and the requested portion content may bere-delivered.

The anycast CDN may also be configured to be operable absent acentralized control layer. Nodes (e.g., delivery cache 412 in FIG. 4) ofthe exemplary embodiment of the anycast CDN framework employ addressresolution. In some implementations, the address resolution system(e.g., DNS) is decoupled from the traffic engineering within thenetwork. In order to ensure uninterrupted delivery of content and/orreduce probability of IP stranding, the CDN may include a resolutionlayer (RL). The RL is in one variant configured to receive informationrelated to one or more routes being advertised (e.g., 422 in FIG. 4).The resolution layer receives a BGP feed in order to monitor routeadditions and/or withdrawals. The RL updates the pool of resolvableroutes based on the route addition and/or withdrawal information. Insome implementations, the RL is configured to reduce routeidentification delays, and/or incorporate route time to live (TTL)information into route pool updates.

In some variants, a pool of advertised route addresses is distributedbetween multiple delivery caches based on a static route-pairadvertising mechanism, e.g., as described in detail with respect toTable 1, below.

Table 1 illustrates the static assignment of a pool of twenty (20)routes comprising addresses 10.0.0.1 through 10.0.0.20 among 10 deliverycaches. The delivery cache 1 is in this example configured to provideroutes 10.0.0.19, 10.0.0.20, 10.0.0.1, 10.0.0.2; the delivery cache 2 isconfigured to provide routes 10.0.0.1; 10.0.0.2, 10.0.0.3, 10.0.0.4.

As may be seen from data presented in Table 1, a given delivery cachecan advertise 20% (e.g., ⅕th) of network routes. In order to ensure thata given route remains available during network operation, any givendelivery address may be advertised by two individual caches (e.g., theaddress 10.0.0.1 is advertised by the caches 1, 2 in Table 1).

Responsive to one of the caches (e.g., 1) becoming unavailable (e.g.,due to a failure and/or a scheduled maintenance event), the remainingcache (e.g., 2) remains available to serve the route 10.0.0.1. Therolling advertisement shown in Table 1 advantageously enablesuninterrupted content provision when a given delivery cache becomesunavailable.

TABLE 1 Example Static Route Advertisement Table Delivery Cache StaticRoute Advertisements 1 10.0.0.19, 10.0.0.20, 10.0.0.1, 10.0.0.2 210.0.0.1, 10.0.0.2, 10.0.0.3, 10.0.0.4 3 10.0.0.3, 10.0.0.4, 10.0.0.5,10.0.0.6 4 10.0.0.5, 10.0.0.6, 10.0.0.7, 10.0.0.8 5 10.0.0.7, 10.0.0.8,10.0.0.9, 10.0.0.10 6 10.0.0.9, 10.0.0.10, 10.0.0.11, 10.0.0.12 710.0.0.11, 10.0.0.12, 10.0.0.13, 10.0.0.14 8 10.0.0.13, 10.0.0.14,10.0.0.15, 10.0.0.16 9 10.0.0.15, 10.0.0.16, 10.0.0.17, 10.0.0.18 1010.0.0.17, 10.0.0.18, 10.0.0.19, 10.0.0.20

The delivery caches are in one embodiment configured in accordance withan internal BGP (iBGP) full-mesh approach. In the iBGP full-meshimplementations, individual router (e.g., 336 in FIG. 3) is configuredto advertise all locally originated routes (e.g., 10.0.0.1-10.0.0.2 inFIG. 3). Such advertisement configuration enables a given networkdelivery cache to access routes advertised by other network caches.Based on the advertised route information, a given cache (e.g., 312 inFIG. 3) implements “intelligent” route management, wherein a given route(e.g., 10.0.0.1) may be withdrawn from the advertised pool by the cache312 based on the route availability from another cache (e.g., 316 inFIG. 3). The route advertising and/or withdrawal configuration describedabove is employed to, inter alia, prevent the stranding of an address.

The delivery caches may be configured (e.g., using the advertised routeinformation described above) to monitor for the stranding of addresses.Responsive to a detection of a stranded route (e.g., 10.0.0.3), one ormore caches (e.g., 312, 314, 316) add the stranded route address to theadvertised pool. Subsequently, individual caches (e.g., 316) withdrawthe route 10.0.0.3 from the advertised pool based on the advertisedroute information that the route is advertised by two or more othercaches (e.g., 312, 314 in FIG. 3). As can be appreciated, the IP routemanagement methodology described herein advantageously providesproactive address stranding prevention in a dynamic fashion, without useof an “artificial floor” that may be associated with the static routeadvertisement option and/or enable dynamic response by the network toinadvertent address stranding.

Route management in the exemplary anycast CDN is configured based on ahybrid of the statically advertised routes and iBGP mesh awareness. Inone variant of the hybrid route management, the delivery caches utilizethe advertised route information (e.g., in the manner described above)in order to monitor route stranding; a fallback network entityadvertises of all of the anycast routes (10.0.0.1-10.0.0.2 in FIG. 3)with an increased route metric. In one or more implementations, thefallback entity is embodied as a centralized server and/or multipledistributed servers. The metric may be configured for example based onone or more of: (i) prefix length, wherein longer subnet masks may bepreferred; (ii) a cost metric, wherein a lower cost may be preferred;and/or (iii) an administrative distance, wherein a lower distance may bepreferred, and/or other. In order to reduce the fallback entity load,the hybrid route management approach prevents traffic routing by thefallback entity unless none of the primary delivery caches advertisingthe route remain available.

The anycast CDN methodology described herein advantageously enablescontent provision via multiple routes, spreading of content requestsbetween multiple delivery caches, automatic and manual trafficengineering, and hierarchical pool selection. As previously noted, ananycast CDN can be implemented without a centralized control layer, andemploy generic hardware and/or software platforms. Accordingly, thenetwork may be scale (vertically and/or horizontally) by adding cachedelivery nodes and/or cache hierarchy levels. In some implementations,one or more cache levels may be disposed off of the network. Popularityindexing and/or cache scoping may also be implemented within the anycastCDN.

Cache selection for the CDN cache configuration described herein canalso be decoupled from address resolution. This advantageouslyalleviates a need for central control plane, simplify network layoutand/or implementation, and enable a client to obtain the IP address ofthe edge cache through any applicable mechanism (e.g., using DNS and/oras a part of the sign on process, and/or other.)

A CDN configured in accordance with the present disclosure alsoadvantageously enable timely “bleeding” (i.e., reduction of traffic) ofexcess traffic by, e.g., adjusting one or more maintenance metrics. Themetrics may comprise for example one or more of (i) remaining capacity,(ii) path length, and/or (iii) local preference. The traffic managementresponsiveness of the CDN described herein may be based, at leastpartly, on reduction and/or elimination of delays that may be associatedwith DNS resolutions and/or client caching expiration operations innetworks configured in accordance with the prior art.

In some embodiments, the CDN is configured to characterize servedcontent by one or more categorization parameters (e.g., “linear”, “VOD”,“popular linear”, “pre-seeded VOD”, “ESPN linear”). A limited-access CDNmay be implemented based on e.g., content (e.g., “adult content”), andmay include a range of addresses not accessible by users of a‘regular-access’ network. Content-based network configurations canadvantageously be implemented in a timely manner without delays that maybe associated with, e.g., flag-day migration of the prior art networks(more statically defined networks).

The exemplary embodiment of the CDN described herein effectuates trafficmanagement by, e.g., automatically rerouting traffic around failednodes, and dynamically and/or automatically managing node traffic toprevent node overutilization, and/or to support maintenance activities.During traffic failover to a next closest delivery cache, traditionalcapacity planning rules (e.g., deterministic failover paths) may beutilized. Additional methods of traffic control can be implemented inthe anycast CDN of the disclosure based on, e.g., traffic metrics. Byway of illustration, dynamic node rerouting between multiple nodesserving content for a given IP address can be employed in order to routearound a failing/overloaded node.

The advertisement of pools of IP addresses enables support forhierarchical caching with a large number of levels (within hardwareconstraints of a given network implementation), the ability to “skip”levels, and/or support for simultaneous hierarchical and edge caching.The provision of real-time alarm functionality and/or event logging canbe implemented through, for example, simple network management protocol(SNMP) traps and syslog messaging.

Authorization functions can be implemented to protect the CDN and originservers. In some implementations, the authorization is configured basedon user identity (e.g., user name, password), CPE device identity (e.g.,MAC address), serving area (e.g., based on user location), usersubscription level, and/or other mechanisms. Content security can beimplemented by using e.g., secure transport protocols (e.g., HTTPS),and/or content encryption using any applicable methodologies known tothose of ordinary skill.

The exemplary anycast CDN may also be configured to seamlessly supporton-net and/or off-net traffic without requiring reconfiguration. Forinstance, on-net and off-net (and in fact, any group of addresses) maybe serviced by any cache simply by advertising reachability to thoseaddresses via BGP. This may take minimal software reconfiguration, butno hardware reconfiguration. Additionally, the CDN may provide supportfor delivery device layer packaging. In other words, since the CDNdescribed is comprised of open-source software and COTS hardware, it ispossible to build additional features onto the delivery cache such asjust in time packaging. Still further, the CDN may allow per-servicefunction and per-path flushing. The CDN could easily support theclearing of content based on a functional pool (i.e., “linear”) or aspecific service (i.e., “CNN”) to remove stale data.

It will be recognized that while certain aspects of the disclosure aredescribed in terms of a specific sequence of steps of a method, thesedescriptions are only illustrative of the broader methods of thedisclosure, and may be modified as required by the particularapplication. Certain steps may be rendered unnecessary or optional undercertain circumstances. Additionally, certain steps or functionality maybe added to the disclosed embodiments, or the order of performance oftwo or more steps permuted. All such variations are considered to bedisclosed and claimed herein.

While the above detailed description has shown, described, and pointedout novel features of the disclosure as applied to various embodiments,it will be understood that various omissions, substitutions, and changesin the form and details of the device or process illustrated may be madeby those skilled in the art without departing from the disclosure. Theforegoing description is of the best mode presently contemplated ofcarrying out the techniques and architectures disclosed herein. Thisdescription is in no way meant to be limiting, but rather should betaken as illustrative of the general principles of the disclosure. Thescope of the disclosure should be determined with reference to theclaims.

What is claimed is: 1.-20. (canceled)
 21. A method of providing contentin a packet-enabled network, the method comprising: assigning an addresswithin the network to the content; associating the address to two ormore nodes of the network, individual ones of the two or more nodesconfigured to deliver the content to a client of the network;advertising two or more routes associated with two or more nodes,individual ones of the two or more routes being characterized by theaddress, and each of the two or more routes comprising at least twoaddress hops; and based on a selection of a given route of the two ormore routes, causing delivery of the content to the client by a node ofthe two or more nodes, the node corresponding to the given route.